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Why are arrays covariant but generics are invariant?
...do with a List<Animal> - you can add any animal to it... including a cat. Now, can you logically add a cat to a litter of puppies? Absolutely not.
// Illegal code - because otherwise life would be Bad
List<Dog> dogs = new List<Dog>();
List<Animal> animals = dogs; // Awooga a...
How to output a multiline string in Bash?
...
Here documents are often used for this purpose.
cat << EOF
usage: up [--level <n>| -n <levels>][--help][--version]
Report bugs to:
up home page:
EOF
They are supported in all Bourne-derived shells including all versions of Bash.
...
Where are sudo incidents reported? [closed]
...place root with your username, in my case ryan, so the log is found with:
cat /var/spool/mail/ryan
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Passing arguments to “make run”
...
run:
@echo ./prog $$FOO
Usage:
$ make run FOO="the dog kicked the cat"
./prog the dog kicked the cat
or:
$ FOO="the dog kicked the cat" make run
./prog the dog kicked the cat
Alternatively use the solution provided by Beta:
run:
@echo ./prog $(filter-out $@,$(MAKECMDGOALS))
%:
...
Multiple aggregations of the same column using pandas GroupBy.agg()
...tion. Renaming and passing multiple functions as a dictionary will be deprecated in a future version of pandas. Details are in the 0.20 change log, which I also summarized elsewhere on SO.
– joelostblom
Jun 3 '17 at 15:13
...
How to replace multiple substrings of a string?
...ent to change the results of previous replacements
For instance:
d = { "cat": "dog", "dog": "pig"}
my_sentence = "This is my cat and this is my dog."
replace_all(my_sentence, d)
print(my_sentence)
Possible output #1:
"This is my pig and this is my pig."
Possible output #2
"This is my dog and...
Why can I use a function before it's defined in JavaScript?
...r combo. Consider updating with a link/excerpt to the ES5 annotated specification. (Which is a bit more accessible.)
– user166390
Jul 16 '12 at 17:58
...
What must I know to use GNU Screen properly? [closed]
...ou're on and which other ones there are. Here is my setup:
[roel@roel ~]$ cat .screenrc
# Here comes the pain...
caption always "%{=b dw}:%{-b dw}:%{=b dk}[ %{-b dw}%{-b dg}$USER%{-b dw}@%{-b dg}%H %{=b dk}] [ %= %?%{-b dg}%-Lw%?%{+b dk}(%{+b dw}%n:%t%{+b dk})%?(%u)%?%{-b dw}%?%{-b dg}%+Lw%? %{=b d...
Why is a 3-way merge advantageous over a 2-way merge?
...ed by two people, one adding moose, one adding mouse.
#File a
dog
cat
#diff b, a
dog
+++ mouse
cat
#diff c, a
dog
+++ moose
cat
Now, if we merge the changesets as we apply them, we will get (3-way merge)
#diff b and c, a
dog
+++ mouse
+++ moose
cat
But if we a...
Can I see changes before I save my file in Vim?
...his in your vimrc or in the plugin directory, open a file, make some modifications without saving them, and do :DiffSaved.
function! s:DiffWithSaved()
let filetype=&ft
diffthis
vnew | r # | normal! 1Gdd
diffthis
exe "setlocal bt=nofile bh=wipe nobl noswf ro ft=" . filetype
endfunction...